Analysis of Risk Factors Associated with Reduced Trough Concentrations of Vancomycin in Relation to Renal Function in a Tertiary Hospital in Japan

Abstract

Background Low trough concentrations of vancomycin (VCM) are common in patients receiving the drug, because patients are often administered relatively low doses of VCM due to its high potential for renal toxicity. However, the clinical risk factors associated with low VCM trough concentration in relation to renal function are unclear. Methods Patients at our hospital who received VCM intravenously from January 2018 to December 2020 were analyzed. The patients were divided into two groups based on their renal function: normal and lower renal function, such as estimated glomerular filtration rate (eGFR) ≧60 and <60 mL/min/1.73 m2, respectively. In each renal function group, patients’ background characteristics, laboratory data and treatments were compared between lower VCM concentration (<10 mg/L) and appropriate VCM concentration (10–20 mg/L) subgroups. Results Among 101 patients with normal renal function, 47 and 54 patients, respectively, showed lower and appropriate VCM trough concentrations. Elderly age, short stature, and higher C-reactive protein (CRP) level were significantly more common in the lower VCM concentration group compared with appropriate VCM concentration group. Among the 45 patients with renal dysfunction, 20 and 25 patients, respectively, showed lower and appropriate VCM trough concentrations. CRP levels were significantly higher in lower VCM concentration than appropriate VCM concentration subgroups. Multivariate analysis showed that insufficient total VCM doses and higher CRP might have affected the lower VCM trough concentration in patients with normal renal function. Conclusion The results of this study suggest that higher CRP might be one of the risk factors associated with lower VCM concentration in both normal and low renal function patients. Severely ill and emergency patients might receive a lower VCM dose due to underestimation of the acceptable VCM dose.